Question

How long does it take $6,000 to quadruple if it is invested at 9.1% interest compounded annually?

a
15.9 years
b
17.8 years
c
37 years
d
222,222.22 years

Answer 1

Answer:

1. 15.9 years

Step-by-step explanation:

You must solve this equation:

$6000 \cdot 1.091^n > 24000$

So $1.091^n > 4$

Take the log left and right:

$\log 1.091^n > \log 4$

use the log property that you can put the exponent in front:

$n \cdot \log 1.091 > \log 4$

$n > \frac{\log 4}{\log 1.091}$

n > 15.917